Sounding board



June 24, 1930. M. R. HUTCHISON 1,767,678

SOUNDING BOARD Filed April 1, 1927 INVENTOR fl/l'ller Reese Hate/viso742 BYQI- ATTORNE\ Patented June 24, 1930 UNITED STATES PATENT OFFICEMILLER REESE HUTCHISON, OF WEST ORANGE, NEW JERSEY, ASSIGNOR, BY MESNEASSIGNMENTS, TO ACOUSTIC PRODUCTS COMPANY, OF NEW PORATION OF DELAWAREYORK, N. Y., A COR- SOUNDIN G BOARD Application filed April 1, 1927.Serial No. 180,182.

This invention relates to new and useful improvements in sounding boardsand methods of tuning and its object is to provide simple means fortuning sounding boards to change their responsiveness to sound waves ofdifferent frequencies. It is well known that the periods of vibrationsof drumheads, strings and the like can be changed by stretching orapplying tension thereto and the more speci 0 object of the presentinvention is to apply this same principle to sounding boards.

Obviously this may be done in several ways and for the purpose of sodescribing my invention that it will be readily understood by thoseskilled in the art, I will illustrate and describe a few simpleembodiments of it, without, however, limiting m self to any specificarrangement. In fact intend no limitations other than those imposed bythe appended claims. By sounding board I mean a vibratory memberpreferably formed of wood or other fibrous material having a naturalfree period of vibration which is either adapted to reflect or to createsound waves.

Referring to the drawings,

Fig. 1 is a sectional plan of a sounding board which embodies thisinvention;

Fig. 2 is a side elevation of the structure shown in Fig. 1;

Fig. 3 is a plan view of a flat sounding board which is to be put undertensionwithout material flexing;

Fig. 4 is a side elevation of such a board as is shown in Fig. 3, withassociated parts for putting it under tension;

Figs. 5 and 6 are a plan and elevation of across its center. 12 and 13are stiff reinforcing pieces across opposite ends of the board which areeither integral parts of the board or are rigidly afiixed to it. 14 and15 are oppositely threaded rods running through the pieces 12' and 13and adjustably engaged by a nut 16 which forms with them a turn-buckle.

By means of the turn-buckle the board may be bowed as shown and to agreater or less extent as desired. Increasing the tension on the rods 14and 15 and the consequent increase in the flexure of the board and itsrib, makes the combination responsive to sound waves of higherfrequencies. So permitting the board and its rib by their inherentresiliency, to assume a position more nearly plane, will make the deviceresponsive to sound waves of a lower register.

Another way of accomplishing the desired result is to stretch thesounding board by some such arrangement as those shown in Figs. 3 to 6.

In Figs. 3 and 4, 20 is a sounding board with a longitudinal rib 21which extends slightly beyond its ends. A link 22 is connected at oneend to an anchorage 23, and at its other end to the rib 21, by means ofa pin 24 which passes through it and through the rib. 25 is aturn-buckle which adjustably connects the other end of rib 21 withanother anchorage 26.

By means of this arrangement the board may be stretched a desired amountto make it responsive to a desired range of sound wave frequencies.

A sounding board without a projecting rib, such as that shown in Figs. 1and 2, or without any rib may be stretched similarly. Figs. 5 and 6 showa board 30 without a longitudinal rib but with stiff reinforcing pieces31 and 32 across its ends which may be either integral parts of theboard or independent pieces rigidly affixed to it. The link 22 isconnected to the piece 31 and the turn-buckle 25 to the piece 32. Themode of operation is obvious.

The desired tension of the sounding board may be obtained by torsion. Anuntwisted board 40, with reinforcing pieces across its ends, is shown inplan view in Fig. 7. Figs. 8 and 9, which illustrate the board twistedout of a pla e, show the upper reinforcing pieces designated byreference numeral a1 and the lower ones by 4-2. These have been movedagainst the resiliency of the board, out of parallelism as viewed fromthe top, to put the board 40 under tension. The board is flexedthroughout but to the greatest extQ'lt at the part thereof midwaybetween the end reinforcements. The distance between the reinforcementsall and i2 is changed somewhat by varying their relative angularity.

The fundamental note of this board is changed by varying the angularitybetween its upper and lower edges.

Although the several methods described herein tend to make the soundingboard so stressed more responsive to one particular frequency, theprimary advantage of my present stem lies in the tact that a certaintension applied to the board will make it equally responsive to a widerange oi. the quencies.

hat I claim is:

2. A resilient soui'iding board. means for stillicning spaced portionsthereof and means for changing the natural relative position of saidstillencd portions.

2. A resilient counding board, means for stiffening opposite endsthereof and means for changing the natural relative position of saidstiit'ened ends.

3. A resilient sounding board. means for stiflcning opposite endsthereof and means for changing; the natural relative distance betweensaid stitl'ened ends.

4:. In a resilient sounding board formed of fibrous material. musicallyinert means for varying the longitudinal tension of the board to rendersaid board responsive to a pinrality of sound wave frequencies.

A resilient sounding board normally responsive to a plurality of soundwave frequencies, including means for varying the longitudal andtransverse tension of the board whereby to render said board responsiveto an increased degree to a specific band of frequencies.

6. A resilient sounding board normally responsive to a plurality offrequencies including means for varying the longitudinal and transversetension of the board to render said board responsive to an increaseddegree to a predetermined band of frequent: lying within the range ofsaid first-named plurality of "frequencies.

In witness whereof, I have hereunto set my hand this 30th day of March.1927.

ZillLLlilt REESE HUTCHISON.

